New 5 Cree Light Bulb at Deal Extreme

Anybody have this yet, and is the $42 worth it?

http://www.dealextreme.com/details.dx/sku.2849

looks like it doesnt output much light for having 5 crees in it. i think they arent driving them very hard, total of 5.8 watts. maybe its a thermal issue. you can get 300 lumens from 2 crees if you drive them harder and heatsink them properly. anyhow, i bet its nice looking light, just kinda pricey for 300 lumens.

The lifespan of 10000hours is not typical for the Cree's, so I think it will have thermal issues.

Best regards

____
Tom

You can get 2 or 3 packs of CFLs for $10. And they are brighter. And are UL listed.

Personally I do not like the tint of the Cree based flashlights I got (L0D-CE, My Little Friend SSC-P4).

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For the little guy the Crees have been available for less than 6 months. The 10000 hours is probably a guesstimate based on Cree's data sheet. They do not have the time to actually test one for a year.
Remember a year or 2 ago when some cheapie multi-led flashlights with a 100,000 hour rating lasted 2 weeks. It seems to be happening to some of DX's bulbs. See this thread:
Led light bulbs from DX
http://candlepowerforums.com/vb/showthread.php?t=161719
I've seen a couple of individual posts prior to the thread.

Long John said:

The lifespan of 10000hours is not typical for the Cree's, so I think it will have thermal issues.

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looks like it doesnt output much light for having 5 crees in it. i think they arent driving them very hard, total of 5.8 watts. maybe its a thermal issue. you can get 300 lumens from 2 crees if you drive them harder and heatsink them properly. anyhow, i bet its nice looking light, just kinda pricey for 300 lumens.
Reply With Quote

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They're probably pushing each one at around one watt each, and there's .8W of driver losses. While it is possible to push a Cree harder than that, for fixed lighting applications, heat buildup becomes an issue, efficiency goes down, and (usually) tint gets worse as those are taken up from 1W of drive power. Either way though, it doesn't make a lot of sense to use one. If you want something with about 50% more light output, similar color temp, better color rendering, and probably better reliability, Home Depot sells 5000K 9W CFLs for about $8 for a 4-pack. They also have a warm white (2700K) and more neutral white (3500K). The advantage of the 9W and under is that those actually are the same size as an incan bulb, most other CFLs are larger.

What LEDs would be an advantage for would be for making single-emitter track light bubls, though probably it woudl be better if someone came out with a good neutral white tint (4000K or so) than using an existing Cree (5500-6500K).

LED lights interest me in dusk to dawn applications. These are the long run lights where saving a few watts adds up in the long run. I have a 13w fluorescent for a porch light that is brighter than is needed and attracts bugs like crazy. But its still the most miserly light I could find to do the job. An LED light at around 5 watts would really please me due to its reliability, no cold-start issues, and because an 8 watt difference for 10 hours a night, every single night, adds up.

I also have two 9w fluorescent lights inside my house that the same basic concept applies to. I'd love to replace each of these with LED of half the wattage.

I've heard the problem with the CFLs is that the ballasts (especially on the cheaper ones) are failing within a year.

My beef with any of these light bulb alternatives is their inability to dim.

riffraff said:

I've heard the problem with the CFLs is that the ballasts (especially on the cheaper ones) are failing within a year.

My beef with any of these light bulb alternatives is their inability to dim.

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Most LED light bulbs can NOT be dimmed.
Check out the LED light bulb section at The_LED_Museum
http://ledmuseum.home.att.net/menutop.htm

The_LED_Museum said:

***VERY IMPORTANT!!!*** DO NOT under any circumstances use this bulb in a fixture equipped with a dimmer switch, whether the dimmer is in the fixture itself or on the wall controlling that fixture. The bulb will overheat and fail if this is done. You don't want rats or rattlesnake eggs...I mean...you don't want an unwanted fire.

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Minjin said:

LED lights interest me in dusk to dawn applications. These are the long run lights where saving a few watts adds up in the long run. I have a 13w fluorescent for a porch light that is brighter than is needed and attracts bugs like crazy. But its still the most miserly light I could find to do the job. An LED light at around 5 watts would really please me due to its reliability, no cold-start issues, and because an 8 watt difference for 10 hours a night, every single night, adds up.

I also have two 9w fluorescent lights inside my house that the same basic concept applies to. I'd love to replace each of these with LED of half the wattage.

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Ikea's got 4 and 7 watt CFLs. 128 and 280 lumens.

CFL? I cannot seem to find what that stands for on the forums here...


So, do I understand correctly? Do not dim led made lightbulbs?

Thanks,
Sean

CFL = Compact Fluorescent Light

seanrolsen said:

CFL? I cannot seem to find what that stands for on the forums here...


So, do I understand correctly? Do not dim led made lightbulbs?

Thanks,
Sean

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i thought i heard that CFLs contain small amounts of mercury. anyhow, leds are very easy to dim, just supply less voltage. is that what the dimmer switch on my 3 way lamp does? if so, there should be no problem dimming led bulbs.

3-way (120 volt) incandescent light bulbs have multiple tungsten filaments that require special sockets and switches to operate the filaments. The filaments are different sizes.

The first switch setting (after off) powers the smallest filament.
The second setting shuts the smallest filament and powers the second filament.

I am trying to verify the following, but I believe it is correct.
The third switch setting applies power to both filaments, simultaneously.

The fourth switch setting returns to off.

This should be more efficient than using a dimmer on lower settings. However, the bulbs are more expensive to purchase.

moon lander said:

i thought i heard that CFLs contain small amounts of mercury.

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A couple milligrams, yes. Mercury is integral to the design of a fluorescent lamp. The mercury vapor is excited by an electric arc, which emits UV radiation. This then strikes a phosphor coating that lines the tube that converts the UV into visible light. White LEDs work the same way, except that they produce blue light, a lot of which goes straight out the front, and some of which is converted to a yellow-green using a phosphor. The problem with this is that the red is deficient. CFLs make up for this by using separate red, green, and blue phosphors. An LED with blue + red and green separate phosphors would be a big improvement.

anyhow, leds are very easy to dim, just supply less voltage. is that what the dimmer switch on my 3 way lamp does? if so, there should be no problem dimming led bulbs.

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So are fluorescent lamps on electronic ballasts -- unlike the old flickery fluorescent lights, the electronic ballasts work first by converting the incoming power to DC. They then "chop" that into a square wave that cycles 20,000 times a second (no flickering). Dimming can be accomplished with pulse-width modulation.

The problem is making a dimmable bulb that works in a standard household dimmer. Some dimmers work by varying the voltage, others work with pulse width modulation, and most trickle some current through at all times, even when they are off. Any number of these can interfere with the integrated ballast in the driver circuits which often relies on a predictable 60Hz 120V power supply to function properly.

So while LEDs and even fluorescents can be dimmed, they will usually require a dedicated ballast with a dimming feature to do so. Personally, I wish there were more such products on the market. Incan is actually much worse to dim from an efficiency standpoint, as the dimmer you go with it, the less efficient it gets. Fluorescent usually stays about the same, and LED is more efficient when dimmed.

LED lights interest me in dusk to dawn applications. These are the long run lights where saving a few watts adds up in the long run. I have a 13w fluorescent for a porch light that is brighter than is needed and attracts bugs like crazy. But its still the most miserly light I could find to do the job. An LED light at around 5 watts would really please me due to its reliability, no cold-start issues, and because an 8 watt difference for 10 hours a night, every single night, adds up.

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True. Another big advantage of LEDs is that you could easily throw a reflctor or optic on and only light up what you need. Fluroescent is great for lighting up a whole room, or a workbench or something, but for spotlighting, LEDs rule for efficiency. The biggest difference with LEDs IMO is their ability to be rapid-cycled. Slapping one of those on a motion sensor for a porch light, where it would run dimmed most of the dim, and get brighter when someone approaches would be ideal. Unlike fluorescent or incan (without soft-start), flashing LEDs off and on a lot doesn't wear them out at all.

This looks like a fixed lighting thread.
Adding to LED Fixed Lighting Index

I just received the LED bulbs I ordered from DX. Nice and bright.
The heatsink gets warm, but not burning hot.

what is the color tint ?

dse93 said:

what is the color tint ?

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It is on the cool side.